1. Field of the Invention
The present disclosure relates to power production in a distribution grid and, more specifically, to a method and apparatus for controlling power production in a distribution grid including a plurality of power producers and a plurality of power consumers, and also relates to a computer-readable medium comprising computer instructions which, when executed by a computer or processor, cause the computer or processor to perform the method.
2. Description of the Related Art
A distribution grid is used to provide a certain amount of electrical power to consumers which have a lack of electrical power due to different reasons, such as voltage sags and swells. Such extra electrical power is taken from different electrical power sources connected to a distribution grid. These electrical power sources are typically direct current sources. Therefore, given that alternating current is used in the distribution grid, it is necessary to perform direct current-to-alternating current conversion prior to providing a desired amount of electrical power to the consumers being in need. For this purpose, i.e., to perform such a conversion process, electrical power converters, also known as inverters, are used. The inverters are placed at the output of the electrical power sources and, thus, are configured to control the amount of electrical power to be supplied into the distribution grid and, consequently, the respective consumers. The amount of electrical power to be provided by each inverter is determined by special control information transmitted to the inverter.
At present, controllable power production in distribution grids including solar battery modules as power producers is of great interest. The solar battery modules are provided with photovoltaic inverters. Control information is transmitted to the photovoltaic inverters to let them know how much power should be supplied into one or more parts of the distribution grid to provide a desired power level for the consumers. However, high-penetration levels of distributed photovoltaic generation in such a distribution grid present several challenges for distribution utilities. For example, the amount of power produced by the solar battery modules in one part of the distribution grid at which there is a lot of solar irradiation can be more than the amount of power produced by the solar battery modules in another part of the distribution grid where there is no or little solar irradiation. Furthermore, the level of solar irradiation can increasingly and temporally change in each part of the distribution grid due to rapidly varying solar irradiation. As a result of this, the voltage sags and swells occur, which cannot be compensated for by slowly responding utility equipment, resulting in a degradation of power quality.
The control of power provided by each photovoltaic inverter gives an opportunity and a new tool for distribution utilities to optimize the performance of the distribution grids, such as by solving optimization problems. The task here is to design an appropriate control scheme for power distribution that will be fast and accurate at the same time. The solution of full optimization problems in such tasks requires a lot of computation time due to a large number of varying parameters and interdependent functions to optimize. However, such a solution will likely be no longer up-to-date when it will be obtained, due to fast changes in production and/or consumption in the distribution grid.
In order to provide better performance of the distribution grid, each inverter can be controlled locally, according to its own measurements (see M. Prodanovic, K., De Brabandere, J, Van den Keybus, T. Green, and J. Driesen, “Harmonic and reactive power compensation as ancillary services in inverter-based distributed generation”, IET Generation, Transmission & Distribution, vol. 1, no. 3, pp. 432-438, 2007), or can be controlled by a central supervising unit (see K. Turitsyn, P. Sulc, S. Backhaus, and M. Chertkov, “Options for control of reactive power by distributed photovoltaic generators”, Proceedings of the IEEE, vol. 99, no. 6, pp. 1063-1073, June 2011), Both approaches present drawbacks, e.g., the local approach exhibits suboptimal performance due to the lack of coordination between agents, and the centralized approach scales badly with the number of devices in the distribution grid, and slowly solves large-scale optimization problems.